CVE-2026-72137

Summary

In the Linux kernel, the following vulnerability has been resolved:

xfrm: nat_keepalive: avoid double free on send error

nat_keepalive_send() frees the keepalive skb whenever the IPv4 or IPv6 send helper reports an error.

That cleanup is only correct before the skb is handed to the output path. Once ip_build_and_send_pkt() or ip6_xmit() takes ownership, the networking stack may already have consumed the skb before returning an error, so freeing it again is unsafe.

Handle the pre-handoff failure cases inside nat_keepalive_send_ipv4() and nat_keepalive_send_ipv6(), where the caller still owns the skb, and keep nat_keepalive_send() responsible only for family dispatch and the unsupported-family cleanup path.

Affected Software

VendorProductVersion RangeStatus
LinuxLinuxf531d13bdfe3f4f084aaa8acae2cb0f02295f5ae < d0a4dc7efa825bce60a8da8f7d43c864a159abdeaffected
LinuxLinuxf531d13bdfe3f4f084aaa8acae2cb0f02295f5ae < 5b0c4c916f202b8fd13d12afb6af62b385622f81affected
LinuxLinuxf531d13bdfe3f4f084aaa8acae2cb0f02295f5ae < a8a7e6a9ff8a4c1f067694ddbd44be67fdf36693affected
LinuxLinuxf531d13bdfe3f4f084aaa8acae2cb0f02295f5ae < 226f4a490d1a938fc838d8f8c46a4eca864c0d78affected
LinuxLinux6.11affected
LinuxLinux0 < 6.11unaffected
LinuxLinux6.12.101 <= 6.12.*unaffected
LinuxLinux6.18.40 <= 6.18.*unaffected
LinuxLinux7.1.5 <= 7.1.*unaffected
LinuxLinux7.2 <= *unaffected

Weaknesses

References